Imagers, such as a video cameras, are used extensively in control systems. The imager may provide a human operator with visual feedback for a remotely controlled procedure, or the imager may provide image input data that is processed by a pattern recognition facility to guide a completely automated process.
Video assisted techniques are used, for example, during surgery to minimize the size of the incision made in the patient's abdominal wall when examining the peritoneal cavity. These techniques include the use of laparoscopes and endoscopes (which may be, for example, arthroscopes). In conventional laparoscopy, a trocar sheath, for example, provides a conduit through the patient's skin into the peritoneal cavity. A tool, such as an electrosurgical tool is removably insertable through the trocar sheath. The tool includes an electrode having an active electrode probe at the distal end thereof. A variety of tip shapes have been used for the probe. The surgery is performed by operating the electrosurgical tool from the proximal end of the probe. Other surgical tools and energy sources (such as ultrasonic tools and argon assisted electrosurgical tools) may be used.
To guide the electrosurgical tool, the surgeon uses a laparoscope which employs a video camera to view the patient's tissue. Typically, the region of interest is illuminated and the color image is transmitted back to the video camera using optical systems inserted through one or more other trocar sheaths at other incisions in the patient's body. Thus, either the illumination source, or the viewing optical system may not always be directed to the same area as the electrosurgical tool during surgery.
During video assisted surgery, the surgeon may use the tool to cut, coagulate or blend tissue. These devices use very high voltages or intense light sources and may cause inadvertent burning. For an electrosurgical tool, burning may be caused by capacitive coupling insulation failure or direct contact between the tip of the tool and the patient's tissue. Direct contact occurs when the surgeon inadvertently or too quickly keys the instrument before having the tip in the correct location. The direct burn is the most severe burn of the three types because it directs a full dose of power to the closest tissue.
The surgeon only sees what is in the field of view of the viewing instrument. However, tools are often out of the field of view, especially when the viewing instrument is brought into a close view of the area of interest. The likelihood of accidentally burning the patient is greater when the electrosurgical tool tip is outside of the field of view of the viewing instrument.
Although the description presented above is in the context of video assisted surgical procedures, the same type of problems may occur in other video assisted operations, for example, operations in which robotic devices must perform tasks because the environment is inhospitable to humans.